The present invention concerns a method for generating a bioactive surface on an endoprosthesis or on the balloon of a balloon catheter. The invention concerns moreover a balloon of a balloon catheter and a balloon catheter.
The so-called “minimally invasive methods” in medicine gain increasingly in significance. In the context of radiology in this connection interventional radiology is to be mentioned that has contributed significantly to the development of minimally invasive techniques and the devices and prostheses of suitable material required for this purpose. For example, today small metal screens as vessel endoprostheses, so-called stents, are inserted by cardiologists as well as radiologists into vessels in order to keep them open. In connection with conventional stents, there is however often a thickening of the vessel wall with consecutive lumen constriction in the area of the stent by cell proliferation or by deposits of cells. Moreover, balloon catheters are inserted by cardiologists as well as radiologists in vessels in order to open them. In connection with these surgical procedures, there is also a thickening of the vessel wall with consecutive lumen construction in the area of the expansion by cell proliferation.
By medication release from the surface of the endoprosthesis or from the surface of the balloon of the balloon catheter, which surface may be provided for improvement of medicament loading and medicament release with a suitable polymer coating, this problem can be counteracted. Typically, an active ingredient that is dissolved in a solvent is applied to the surface of the endoprosthesis or the surface of the balloon of the balloon catheter, and the solvent subsequently evaporates. The active ingredient is then located on the surface.
Possibilities for obtaining in comparison thereto an improved adhesion of the active ingredient on the surface, are disclosed in the documents U.S. Pat. No. 5,102,402 and U.S. Pat. No. 6,129,705. The document U.S. Pat. No. 5,102,402 discloses a balloon catheter coated with medicaments. In this connection, in a first variant microcapsules filled with an active ingredient or medicament are enclosed by folds in the balloon surface and in this way mechanically held in their respective position. In a second variant the microcapsules are glued by means of a bonding agent to the balloon surface. In the context of this document, uncoated active ingredient crystals are also viewed as microcapsules.
In the document U.S. Pat. No. 6,129,705 a balloon catheter and a stent are disclosed whose surfaces have each a coating in which microcapsules that are filled with an active ingredient are completely embedded. In one embodiment variant a balloon catheter is described having in its uncoated surface microcapsules filled with an active ingredient extruded during the manufacturing process. However, filling the active ingredient into microcapsules and the subsequent attachment or embedding of the microcapsules on the balloon surface or stent surface are comparatively complex and thus expensive methods.
It is therefore a first object of the present invention to provide an advantageous method for generating a bioactive surface on an endoprosthesis or on the balloon of a balloon catheter. It is a second object of the invention to provide an advantageous balloon of a balloon catheter. A third object resides in providing an advantageous balloon catheter. A fourth object resides in providing an advantageous endoprosthesis.